If a student from my school did that I would say big deal, but looking at the interface myself and knowing fully well it comes from Microsoft, I'll say "So What". Like Allen said, it's apparent Microsoft only trailed google by tweaking the priority inbox feature (In a very nice way).
However, It affords a lot of space and I'll like to see how the desktop application will learn from the webmail services by giving more room to read email. In my opinion, Microsoft only wants the outlook.com to share an interface similar to windows8, no more, and no less. At the very end again, I'll say "No Big Deal"